How do I assign a pin location with empty source code that contains only port declarations?
For NGDBuild, you must use the "-u" option in order to run this flow.
From Project Navigator, right-click "Translate" and select "Properties."
Check the box to "Allow Unexpanded Blocks", then start PACE.
Using Leonardo Spectrum and Synplify, you can begin to LOC pins without the "-u" option. After you select the UCF file, start PACE by double- clicking "Assign Package Pins" from the process window. The following error will then be reported:
"ERROR:XdmHelpers:828 - File 'c:/f21/iseexamples/tester/_ngo/and_gate.ngo' is not in NGD or XDB format. Error: NGDBUILD failed."
Start PACE again by double-clicking "Assign Package Pins". PACE will start and indicate that there are unconnected ports. You can then click "Yes" to enable the I/Os to be shown. PACE will show input ports as being undefined; output ports will be noted as output ports.
NOTE: This procedure will not work for XST.
Launch PACE/Floorplan Editor from the command line (pace) and load in the empty source code. PACE can perform pin location and write out a UCF for your port declarations.